Humidifying apparatus



Dec. 16, 1941. c. E. ROBB 2,266,267

nummwme APPARATUS Filed Feb. 25, 1958 s Sheets-Sheet 1 hen/07 e3 I Babb 00W MZW 5,

Dec. 16,1941. c. E. ROBB HUMIDIFYING APPARATUS Filed Feb. 25, 1938 I HUN D 16, 1941, c. E. ROBE 2,266,267

HUMIDIFYING APPARATUS Filed Feb. 25, 1938 3 Sheets-Sheet 5 0201 12 l l gi 5 Patented D... 16, 1941 UNITED STATES PATENT OFFICE nnrnnmx zlrmrus l V Charles E. R0111), Rock Island, Ill. Application February 25, 1938, Serial No. 192,491

16 Claims.

This invention relates to a humidifying appa ratus and it is concerned particularly with a highly eflicient apparatus that can be employed with all types of heating systems.

One of the big problems in humidifying equipment, particularly equipment used with heating devices that have already been installed in buildings, though the problem is also present in new buildings, is to find an apparatus which can be used with every variety of heating equipment, which can be made and installed for a reasonable cost, one that is simple and foolproof yet automatic in its operation, one that will operate continuously without becoming clogged from deposits resulting from evaporated water, and one that is eiiicient and of sufficient capacity to give proper humidiflcation.

T-he difiiculty with prior devices has been that they are quite expensive, that they are not adapted to different types of heating systems, that they soon clog with salt deposits and require continuous servicing and that, above all. they do not have sufiicient capacity to give the degree of humidification desired. The present invention has been devised to overcome these diliiculties and it accomplishes this object with a high degree of efliciency and completeness.

' The general object of the invention is to provide an improved humidifying apparatus.

A more particular object is to provide a humidifying apparatus that can be used with any type of heating system.'

Other and more particular objects will appear from the following specification and drawings.

An embodiment of the invention is shown in the accompanying drawings, in which:

Figure 1 is an illustration of the apparatus ap-- plied to a domestic heating system;

Fig. 2 is a partial plan view of the unit that vaporizes the water;

Fig. 3 is an end view of said unit;

Fig. 4 is a side elevation of a float valve used with the apparatus;

ill

heating furnace l having a fire boxor heating chamber II and an exit flue or pipe l2. The furnace may heat water, or air, or it may generate steam, it being immaterial as far as the present invention is concerned what type of heating is used.

Mounted in the flre box II is a small steam generating device comprising a hollow metal body I! which preferably has flns on its outersuriace. Connected to this steam generator is that'passes out of the fire boxand which, ordinarily, supports the steam generator. The pipe l6 extends horizontally a short distance to where an elbow I! or other similar connectlon joints it to the necessary piping to, connect it to the humidifying unit 20, which piping, in the installation, illustrated, is a vertical riser This humidifying unit 20 is of the type dis closed in my copending application Serial No. 14,115, filed April 1, 1935, now, Patent No. 2,124,- 510, of which the present application is a continuation in part. Briefly, it comprises a rectangular metal body having an enclosed hollow chamber 2| at the bottom for receipt of steam or other heating mediums. The top 22 of this chamber forms the bottom of an open rectangular recess 23 (Fig. 2) which receives the water to Fig. 5 is a sectional elevation of a a solenoid valve used with the apparatus;

Fig. 6 is a sectional elevation of a pressure control device used with the apparatus;

Fig. 7 is a side elevation of a heat controlled time switch used with one form of the apparatus;

Fig. 8 is a side elevation of another form of heat controlled time form of the apparatus; and

Fig. 9 is an illustration similar to Fig. 1 showing another form of the invention.

be evaporated. The dividing wall 22 is thus in direct contact with the steam on one side and the water to be evaporated on the other, said wall being coextensive with substantially the entire vaporizing surface of the humidifying unit. Water is maintained in a relatively thin layer on the top of the dividing wall 22 with the result that it evaporates very rapidly. It has been found in practice that this humidifying unit has an exceedingly high capacity.

Water is fed to the recessed top 23 of the unit through a supply pipe 24 controlled by a solenoid valve 25 which is adjusted so that, when waterto flow slowly into said open, it allows water chamber. Any suitable form of solenoid i5 valve may be used, one being illustrated in Figure switch used with another 5 where'the electric winding 26 controls the plunger 21 that governs the valve 28, the valve being urged to closed position.

The solenoid valve 25 is controlled by a humidostat 29- located in the room whose humidityis to be controlled. Any suitable form of humidostat may be used, which, when the humidity in the room getsbelow a predetermined valuewill close an electric circuit. An adjustment is The invention is shown applied to a domestic 5 Preferably Pmvided the humidostat 50 that the degree of humidity at which the circuit is closed may be varied.

In order to prevent overflow and to maintain the water in the humidifying unit 2|) in a very thin layer over the dividing wall 22, a control is provided that is responsive to the water level. This is preferably a float switch 30 that is arranged to control the circuit of the solenoid valve 25. Any suitable form of float switch may be used, one such being illustrated in Fig. 4 where a float 3| is arranged to tilt a mercury switch 30 when the water level reaches a predetermined height. The float is preferably located in the small float chamber 33 at the end of the humidifying unit 20, as illustrated in Figures 2-4. This is done in order to provide a sufficient depth of water to operate the float 3|. The layer of water in the recess 23 of unit 20 is very thin and not well adapted to operate a float.

The electric circuit for these devices is as follows: Starting with the transformer 34, the line 35 goes to the float switch 30, the line 36, the solenoid valve 25, the line 31, and the humidostat 29, with the return 38 going to the transformer.

The solenoid valve 25 is normally closed, and it is controlled automatically both in the matter of supplying too little or too much water to the unit 20. When the humidity in the room drops below a predetermined value, the humidostat 29 closes the circuit of the solenoid valve 25; and, assuming that the water level in unit 20 is not too high, the solenoid valve 25 will be: energized and it will open to slowly supply water to the humidifying unit. The solenoid valve may later close automatically under one of two controls. For example, if the water is supplied very slowly and evaporated rapidly, as it usually is, the water in the unit 20 will not reach a level sumcient to operate the float switch 30. But, when enough water has been evaporated to increase the humidity in the room to the-desired degree, the humidostat 29 will open the circuit of solenoid valve 25, whereupon the water will be shut off. On the other hand, if, after the solenoid valve has been opened by the humidostat as above explained, the water is supplied too rapidly, or if the relative humidity is very low and it is desired to operate at maximum'capacity, the water in unit 20 will reach'a level sufllcient to operate the float switch 30 which will then open the circuit of solenoid valve 25 and shut off the water. Thus the supply of water to the humidifying unit is automatically controlled in accordance with the humidity conditions of the room or building, and a safety control is provided to prevent overflow. It is pointed out that there is no overflow from the humidifying unit to become clogged as so often happens in poor devices. Instead, the supply of water is efficiently controlled.

The steam generator IS, the pipes I6 and I8, and the chamber 2| of the humidifying unit 20 form a closed steam system. A small amount of water is placed in this system which, when converted into steam, passes upwardly into the chamber 2| of the humidifying unit where its heat is expended in evaporating the thin layer of water in the recessed top of said unit. When the steam condenses, the water of condensation runs back through the pipes I6 and I8 to the generator I5, where it is again converted to steam, the process continuing indefinitely. Very little heat is required to reconvert the condensed water intosteam. The generator being very hot, the returning condensed water is converted into steam almost instantly. Only a few ounces of water are used and the supply seldom needs to be replenished, though provision is made for automatically replenishing it and controlling the operation of the system, as will be presently explained. An important advantage of using such a small amount of water and of using it over and cluding such other mediums.

In order to supply a small quantity of water, when required, to said closed steam system, a

- water supply pipe 40 is connected to the pipe I6 through a solenoid valve 4| and a hand regulated sight feed 42, the latter governing the rate of flow when the solenoid valve 4| is open. The sight feed 42 is usually not disturbed after being set. The solenoid valve 4| is urged to closed position and is opened when the solenoid is energized. The circuit for the solenoid is governed auto matically by two devices, one being a pressure controlled device 43 and the other a heat responsive time control 44.

The pressure controlled device 43 is connected to the pipe I5 of the steam system and it is provided with mechanism responsive to the steam pressure in said system for closing an electric circuit when the pressure reaches a predetermined value. In the present invention the pressure controlled device is preferably adjusted so as to be responsive to about two pounds of steam pressure but if the space to be humidified is large,

the device may be set for higher pressures, such,

for example, as up to ten pounds. The higher the pressure, the higher the temperature of the steam available to vaporize the water in the humidifying unit; and thus the setting of the pressure device 43 governs to some extent the rapidity of the water vapor supply to the space to be humidified. Any one of a number of wellknown pressure-control devices may be used. One such device is illustrated in detail in Fig. 6. It comprises a pressure-responsive bellows enclosed within the housing 45 and arranged to control a mercury switch 46. The device is adjusted so that the mercury switch closes a circuit when the pressure in the system is at zero or below a predetermined amountfor example, below two pounds. 'When the pressure generated in the system reaches the predetermined amountfor example, two poundsor exceeds it, the mercury switch 46 is tilted so as to open the circuit that controls the solenoid valve 4|. Thus, as long as there is enough water in the closed system to permit two pounds of steam pressure to be generated, the pressure controlled device 43 will keep the circuit of the solenoid valve 4| open and no further water can be supplied to said system. The steam generator in the fire box is ordinarily so hot that the returning condensed water is converted into steam instantly with a flash action so that pressure balance in the system is nicely maintained.

When the furnace is first started and the system is cold, there is, of course, no pressure in the closed steam system. The pressure controlled device 43 closes the circuit of the solenoid valve at that time. But there likely is plenty of water in the system. If so, the solenoid valve should .not en. To take care of this condition means {is provided which is responsive to the activity of the furnace. This means preferably pressure never becomes dangerous In order to takes the form of a heat responsive time switch" 44, the same being preferably located in the stack or due l2. Thisheat-responsive time switch is shown in detail in Fig. '7. It comprises a curved plate 50 shaped to fit the outside of the pipe l2.

This plate has a hollow tube fixed to it which extends into the interior of the pipe i2. Positioned within the tube 5! is a rod 52 whose inner end is connected at 53 to one end of a heatresponsive element 54 which is a bimetallic element that expands and contracts in response to temperature variations. The other end of this bimetallic element is fixed to a nut 55 threaded onto the end of the tube ii. The outside end of the rod 52 is fixed to a stem 56 holding a mercury tube switch 51 for closing an electric circuit.

This control device is adjusted so that when there is no combustion activity in the furnace the circuit is open but, after combustion activity starts, and ordinarily in about fifteen minutes, the element 54 becomes heated sufficiently to turn the rod 52 far enough to close the switch 51. When the apparatus is installed, the furnace is 'run for fifteen minutes, after which the switch is closed by means of a set screw to thereby adjust it so as to always close in about fifteen minutes and to open almost instantly after the furnace is shut down.

The circuit for the above devices is as follows: Starting with the transformer 34, the connection is through the lines 35 and 60 to the pressure controlled switch 43, from which a line 6| leads to the solenoid valve. From the valve 4| a line 62 leads to the heat responsive switch 44 and from the latter a line 63 leads tothe other side of the transformer.

The manner in which the apparatus operates will be best understood by following through an operation.

Assume that the furnace is started and that prevent the pressure exceeding a determined value. an exhaust. or relief, valve 14 is provided which releases the pressure when it exceeds a value of about thirty pounds and drains the exhaust downwardly through tube II. In practice, this condition does not often occur because the water supplied to the humidifying unit II is allowedto flow slowly and the humidlfying action is a continuous one, the air in the room changing fairly rapidly. By adjusting the valve II the flow of water can be made such that a continuous operation of the humidifying apparatus keeps the humidity at just about the right amount.

When the apparatus starts under the conditions above-assumed, the solenoid valve 4| is in its normal closed condition and no water is supthe proper amount of water is in the closed steam system to generate about two pounds of steam pressure. Assuming that the humidity in the room is low, the solenoid valve 25 will have been opened and the recessed top of unit 20 will have a thin layer of water in it, said unit having been filled until the float switch 30 operates to open the circuit of solenoid valve 25 to shut off the water supply. Steam is quickly generated in the generator 15, from which it passes through the pipes i6 and I8 to the chamber 2|, where it vaporizes the water in unit 20, said vapor passing up into the room to increase the humidity. The steam in chamber 2| condenses and runs back through the pipes i1 and it to' the generator i5, where it is again converted into steam and passes up as before, a continuous circulation occurring for continuous operation of the humidifying unit. As the water in the humidifying unit 20 evaporates, the float switch 30 operates to close the circuit of solenoid valve 25 to allow more water to slowly flow tothe unit 20-. If the humidity should exceed the desired value the humidostat 29 operates to open the circuit of the solenoid valve 25, whereupon no further water is supplied to the humidifying unit 20. In that event, the closed steam system continues to operate to heat the humidifying unit 20 without evaporating any water. If the heat of the steam is not absorbed in evaporating water, the pressure in the system tends to increase but. owing to the small amount of water in said system, this plied to the closed steam system. The solenoid valve is closed because its' circuit is open at the heat-responsive control device 44 even though said circuit is closed at the pressure control device 43. After about fifteen minutes, the heatresponsive switch 44 closes but, in the meantime, the pressure in the system should have exceeded two pounds, or such amount as is determined by the-pressure switch 43, and the pressure controlled switch 43 should have opened the circuit of the solenoid valve 4i so that said valve remains closed. Thus, the apparatus is given, or

spotted, a certain time within which to get into action after which more water will be supplied to the steam generating system if the sure is not raised to the desired amount.

In the event there should not be enough water in the closed system to generate the desired steam pressure. the pressure switch '43 will'not open the solenoid circuit. Consequently, when the time switch 44 closes at the expiration of fifteen minutes, the solenoid valve 4| will be opened and water will be allowed to slowly drip. into the closed system. As soon as enough water has en-' tered to permit the, desired steam pressure to be generated, the switch 43 will open the circuit of the solenoid valve 4! andthe water supply will be cut off again.

The time element in the closing of the switch 44 prevents water from being introduced into the steam system before the latter has had time to generate the desired pressure even though there is enough waterin the system for this purpose.

The system is given a time interval within which to generate the desired steam pressure but, if it does not generate this pressure within said time, then the solenoid valve operates to slowly introduce more water into the system.

When combustion activity in the furnace ceases, steam pressure in the closed system drops.

because there is such a small amount of water in it, and the parts start cooling off. The pressure switch 43 then closes and might. if the switch 44 remained closed, allow more water to go into the steam system. The flue cools off very rapidlyand the time switch .44 is adjusted so that, as soon as the temperature drops below what is normally maintained in the flue, the switch immediately opens. It has been found that this switch can be adjusted'to open forty seconds after the furnace is shut down, which is prior to the time that the switch 43 will close.

The positioning of the control'switch 44 has been shown as in the flue or stack to the furnace. It will be understood that this switch may be otherwise located. In fact, in so far as the present invention is concerned it is merely necessary presto hav a switch that is responsive to the activity of the furnace. In other words, one that will be closed within a certain time after the furnace has started and will be opened immediately upon the stopping of the furnace. A switch responsive to temperature conditions in the stack has been found to operate efilciently, and is preferred, but it is to be understood that the invention is not limited to a device of this type but will operate also with a mechanical device responsive, for example, to whether or not an oil burner or coal stoker is running, or to the activity of a gas burner.

The system may be drained by a pipe controlled by a hand valve 18. Air may also be vented out of the system by means of the vent valve 11.

Figure 9 shows a modified construction in which the circuit for the solenoid valve 4|, in addition to passing through a control switch 44 in the furnace flue, passes through a time limit switch 80, sometimes called a spotter because it spots the apparatus a certain time within which to act. This time switch is illustrated in detail in Fig.8. It comprises a bi-metal helical coil 8| connected to a mercury switch 82 in the circuit of the solenoid 4|. The coil 8| is responsive to the temperature of the steam pipe l6. Normally, the switch 82 is open. but within a predetermined time, such, for example, as fifteen to twenty minutes, the pipe l6 will heat the element sufficiently to cause the switch 82 to close. The function of this time switch is to spot the apparatus a predetermined time within which to get into action before any water is allowed to enter the closed-pipe system. At the start of operations there ls-no pressure in the closed system and the circuit of solenoid valve 4| is closed as far as the pressure switch 43 is concerned. The circuit for said valve is open at the control 44 but, in this modification, the circuit at 44 is closed relatively soon. If the spotter 80 were not provided, thecircuit of solenoid valve 4| might be closed too soon and water would be allowed to fiow into the closed system too soon. But, with the spotter 80 present, the circuit will not be closed until after a predetermined period, say fifteen minutes. In the meantime, if the system has enough water in it, the

pressure controlled switch 43 will have opened.

If there is not enough water in the system, switch 43 will not have opened, and, then, when switch 82 closes, the solenoid valve 4| will open to supply the necessary water. When the furnace is shut down, the circuit of the solenoid valve 4| is opened by the control switch 44, as heretofore explained, the time switch 82 remaining closed until it is cooled off.

In this modification, the spotter" or time switch 80 is responsive to activity in the furnace by being responsive to the heat of the steam system, while the opening of the circuit by the switch 44 is responsive to cessation of activity in the fcrnace by being responsive to the flue temperature.

This modification also shows a different arrangement for conveying the water vapor from the humidifier to the room to be humidified. The humidifying unit is covered by a housing 90 open on one side at 9| to permit air to enter. This housing has a tube 92 connected to it, which extends to the room to be humidified. With this arrangement, the humidifying unit 20 may be located some distance from the room and the vapor conveyed to said room. The opening in the housing permits enough air to enter so that the water vapor entering the room will not be so noticeable as would otherwise be the case. This housing construction can also be used with the form of the invention shown in Fig. 1.

The advantages of the invention, in all its forms, are quite numerous. The first cost is relatively small particularly when the capacity of the apparatus is considered. The cost of the upkeep is practically nothing, or at least negligible. The fact that the closed steam system uses such a small quantity of water avoids difficulties that are ordinarily encountered with the deposits of salts that clog such a system. Furthermore, the automatic control of the water to the humidifying unit, including the overflow control, avoids the deposit of salts in drainage pipes or overflow apparatus. Any deposits resulting in the evaporation of water are in the recess on top of the humidifying unit, which recess is easily accessible and easily cleaned because it ordinarily has an enameled surface. In addition the system is completely automatic and requires no attention. There are no delicate parts to frequently get out of adjustment and repair. The advantage of having an apparatus that does not clog because of the deposit of salts is a very important one from a practical standpoint. Many humidifyingsystems are theoretically satisfactory but, when put into practical operation, soon clog with deposits of salts so that continual attention is necessary and the user finally becomes disgusted and throws them away. The present invention has been devised with this in mind and it comprises a combination of elements that avoids this dimculty.

Another important advantage is that humidification takes place so quickly and at such a rate and volume that proper relative humidity is maintained, a result that is not possible with prior humidifiers so far as I am aware. For example, it is well known that, when the temperatare of the air in a room is raised, the capacity of the air to absorb moisture is increased. With the ordinary humidifier having small capacity, and acting slowly, the heating system for the room increases the capacity of the air to absorb moisture much more rapidly than the moisture is supplied, with the result that the proper degree of humidification is not obtained until long after the room has reached a comfortable temperature. But, in order to reach this temperature, the air has had to have been heated to a temperature that is comfortable with the air dry whereas, if the humidity had been proper at all stages, the temperature to which the air would have had to have been raised to be comfortable would have been several degrees lower. With the present invention, when the furnace is started, the humidifier acts more quickly and more rapidly to humidify the air than the furnace acts to heat the air. The very small amount of water in the closed system is heated quickly. Its heat is transferred to the humidifying unit at once and the latter, being quick acting and of high capacity, acts quickly to humidity the air to the desired de ree. This action continues as the air is heated, and the result is that the air in the room need not be heated to as high a temperature tobe comfortable as would otherwise be the case. Needless to say this results in a very considerable saving in fuel as well as increasing the comfort and health of those using the room. This method of humidifying the atmosphere of aroom aheadoftheheaflngisnewinsofaras I amaware, andit isan importantpartotmy invention. i, 1

It is to be understood that the constmction shown is for purposes of illustration only and that variations may be made in it without departing from the spirit and scope of the invmtion as defined by the appended claims. -I claim: a V

1. A humidifying apparatus comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamber for receiving steam from said generator to vaporize water supplied to said humidifier, a closed piping between said generating device and said chamber whereby a closed steam system is provided, means for supplying water to said steam system, means governed by the steam pressure in said system for controlling said water supply to said system, and means governed by said furnace in response to its operation for also governing said water supply.

2. A humidifying apparatus comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said humidifier,-a closed piping between said generating device and said chamber whereby a closed steam system is provided, means for supplying water to said steam system, means governed by the steam pressure in said system for controlling said .water supply to said system, and means governed by the heat generated by saidfurnace for governing said water Supply to said system.

3. A humidifying apparatus comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said humidifier, a closed piping between said generating device and said chamber whereby a closed steam system is provided, means for supplying water to said steam system, means governed by the steam pressure in said system for controlling said water supply means to cause water to be supplied to said system when the steam pressure therein is below a predetermined value, and means responsive to the operation of said furnace for controlling said water supply means to prevent water being-supplied to said system until a predetermined time has elapsed after operation of said furnace has started, said furnace responsive means also acting to prevent water being supplied to said system when operation of said furnace ceases.

4. A humidifying apparatus comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said humidifier, a closed piping betweensaid generating device and said chamber whereby a closed steam system is' provided, 7 means for supplying water to said steam system, means governed by the steam pressure in said system for controlling said water supply to cause water to be supplied to said system when the steam pressure therein is below a predetermined value, and means responsive to heat generated by said furnace for controlling said water supply to prevent water being supplied to said system until a predetermined time has elapsed after the starting of said furnace, said heat responsive means also acting to prevent water being supplied to said system as soon as operation of said furnaces ceases.

5. A humidifying apparatus comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said humidifier, a closed piping between said generating device and said chamber whereby a closed steam system is provided, means for slowly supplying water to said steam system, means urged to a condition to enable said water supp y but governed by the steam pressure in said system to disable said water supply means when said steam pressure exceeds a predetere I mined value, and means urged to a condition to disable said water supply but responsive to heat generated by said furnace and operating within a predetermined time after said furnace is started for enabling said water supply means, said temperature responsive means also acting to disable saidpwater supply means when said furnace ceases operating. 1

6. A humidifying apparatu comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamher for receiving steam to vaporize water supplied to said humidifier, a closed piping between said generating device and said chamber whereby .a closed steam system is provided, a solenoid valve for controlling the water supply to said system, said valve being urged to closed position but being opened when the circuit of said solenoid is energized, means responsive to the steam pressure in said system for opening the circuit of said solenoid valve when said pressure exceeds a predetermined value, and means normally opening said circuit responsive to the operation of said furnace for closing said circuit within a predetermined time after operation of said furnace is started and for opening said circuit within a predetermined time after the operation of said furnace ceases.

7. A humidifying apparatus comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said unit, a closed piping between said generating device and said chamber whereby a closed steam system is provided, a solenoid valve for controlling the water supply to said steam system, said valve being urged to closed position but being opened when said solenoid is energized,

. means responsive to the pressure in said system for opening the circuit of said solenoid valve when the pressure exceeds a predetermined value, and means normally opening said circuit but responsive to heat generated by said furnace for closing said circuit within a predetermined time after said furnace is started and for opening said circuit when operation of said furnace ceases.

8. A humidifying apparatus comprising a selfcontained unit including a closed steam system and having a steam generating device adapted to be positioned in a furnace and a humidifier having a closed chamber by means of which steam may be utilized to vaporize water supplied to said humidifier, normally disabled means for supplying water to said closed system, means responsive to the operation of said furnace for enabling said water supply means within a predetermined time after combustion activity starts in said furnace and for disabling said water supply means when the combustion activity ceases, and means responsive to the steam pressure in said system for disabling said water supply means when said pressure exceeds a predetermined value.

9. A humidifying apparatus comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said humidifier, a closed piping between said generating device and said chamber whereby a closed steam system is provided, a normally disabled means for supplying water to said system, means responsive to the temperature of aportion of said system for enabling said water supply means within a predetermined time after combustion activity in said furnace starts, means responsive to the steam pressure in said system for disabling said water supply means when said pressure exceeds a predetermined value, and means responsive to the combustion activity of said furnace for disabling said water supply means when combustion activity in said furnace ceases.

10. A humidifying apparatus comprising a small steam generating device adapted to be positioned in a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said humidifier, means governed by the humidity of the space to be humidified for slowly supplying water to said humidifier, a closed piping between saidgenerating device and said chamber whereby a closed steam system is provided, means controlling the water supply to said system, said water supply means being normally conditioned to shut off the water supply to said system, means responsive to the operation of said furnace for enabling the water supply means for said system within a predetermined time after operation of said furnace starts, and means responsive to the pressure in said system for disabling the water supply means for said system when the pressure in said system ex ceeds a predetermined value, said furnace responsive means also disabling said water supply means for said system when operation of said furnace ceases.

11. A humidifying apparatus comprising a small steam generating device adapted to be positioned in the fire box of a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said humidifier, means governed by the humidity of the space to be humidified for slowly supplying water to said humidifier, a closed piping between said generating device and said chamber whereby a closed steam system is provided, a normally disabled means for slowly supplying water to said steam system, means responsive to the heat generated by said furnace for enabling the water supply means for said systems within a predetermined time after said furnace is started, and means governed by the pressure in said system for disabling said water supply means for said system when said pressure exceeds a predeter mined value, said heat responsive means also disabling said water supply means for said system when said furnace ceases operation.

12. A humidifying apparatus comprising a small steam generating device adapted to .be positioned in a furnace, a humidifier having a closed chamber for receiving steam to vaporize water supplied to said unit, means for slowly supplying water to said humidifier, a normally closed solenoid valve controlling said water supply, a humidostat in the space to be humidified and a float switch for said humidifier, both controlling the circuit of said solenoid valve, a closed piping between said generating device and said chamber whereby a closed steam system is provided, means for supplying water to said system,

a normally closed solenoidv valve for controlling the water supply means for said system, means responsive to the heat generated by said furnace for closing the circuit of said solenoid valve in the water supply to said system within a predetermined time after said furnace is started, and means responsive to the. steam pressure in said system for opening the circuit of said valve when the pressure exceeds a predetermined value, said furnace responsive means also opening the circuit of the solenoid valvein the water supply for said system when operation of said furnace ceases.

13. An apparatus for heating and humidifying the atmosphere of a room comprising a heat source at a distance from said room, means for conveying heat from said heat source to said room to heat the same, means for maintaining a thin, relatively immobile layer of water of relatively large area in direct communication with the atmosphere of said room, and means comprising a steam generating device characterized by a flash-like action directly exposed to the heat of the source and piping for conveying the steam into heat exchanging relation with the water and operating, when said heat source is rendered active to heat said room, to immediately and rapidly convey heat from the device to the water and cause it to be vaporized at such speed and in such quantity as to humidify the atmosphere of said room to the desired degree in advance of the heating of said atmosphere, whereby therelative humidity of the atmosphere of said room will remain substantially constant while said atmosphere is being heated.

14. An apparatus for heating and humidifying' the atmosphere of a room comprising a heat source at a distance from said room, means for conveying heat from said heat source to said room to heat the same, means for maintaining a thin, relatively immobile layer of water in direct communication with the atmosphere of said room, means comprising a steam generating device characterized by a flash-like action directly exposed to the heat of the source and piping for conveying the steam into heat exchanging relation with the water and operating, when said heat source is rendered active to heat said room,

to immediately and rapidly convey heat from the device to the water independently of said means Y for conveying heat to said room so that said water will be vaporized at such speed andin such quantity as to humidify the atmosphere of said room to the desired'degree in advance of the heating of said atmosphere, whereby the relative humidity of the atmosphere of said room will remain substantially constant while said atmosphere is being heated, and means controlling the effective operation of said water heating means in accordance with whether said heat source is active or inactive.

15. An apparatus for heating and humidifying the atmosphere of a room comprising a heat source at a distance from said room, means for conveying heat from said heat source to said room to heat the same, a humidifying unit located in direct communication with the atmosphere of said room to deliver water vapor directly thereto, said unit having portions adapted to hold a thin, relatively immobile layer of water of relatively large area, means controlled by the humidity of said atmosphere for causing said layer of water to be maintained in said humidify-;

ing device characterized by a flash-like action directly exposed to the heat of the source and piping for conveying the steam into heat exchanging relation with the water and operating, when said heat source is rendered active to heat said room, to rapidly convey heat from the device to said humidifying unit so that said unit will humidify the atmosphere 01. said room to the desired degree in advance of the heating of said atmosphere, whereby the relative humidity of the atmosphere of said room will remain substantially constant while said atmosphereis being heated.

16. An apparatus for heating and humidifying the atmosphere of a room comprising a heat source at a distance from said room, means for conveying heat from said'heatsource to said room to heat the same, a humidifying unit located in direct communication with the atmosphere of said room to deliver water vapor directly thereto, said unit having portions adapted to hold a thin, relatively immobile layer oi. water of relatively large area, means controlled by the humidity of said atmosphere for causing said layer of water to be maintained in said humidifying unit, and means comprising a steam generating device characterized by a flash-like action directly exposed to the heat of the source and piping for conveying the steam into heat exchanging relation with the water and operating, when said heat source is rendered active to heat said room, to rapidly convey heat from the device to said humidifying unit independentlyof the means for conveying heat to said room so that said unit will humidify the atmosphere of said room to the desired degree in advance of the heating of said atmosphere by said heat source, whereby the relative humidity oi. the atmosphere of said room will remain substantially constant at said desired degree while said atmosphere is being heated, and means responsive to the temperature of the flue gases for controlling the effective operation or saidwater heating means in accordance with whether said heat source is active or inactive.

CHARLES E. ROBB. 

